SU1589367A1 - Frequency synthesizer - Google Patents

Abstract

The invention relates to radio engineering. The purpose of the invention is to expand the range of output frequencies. The frequency synthesizer contains a reference oscillator 1, a pulse subtraction unit 2, a counter 3 with a variable conversion factor, the first and second sawtooth generator (GPN) 4 and 8, the comparator 5, accumulator 6 and adder 7 codes. The steepness of the sawtooth voltage of the first and second FPGs 4 and 8 depends not only on the current delay code XI from the output of accumulating adder 6, but also on the number of the synthesized frequency Q defined by the second input of the adder 7. With the same voltage variation law at the outputs of the first and second GPN 4 and 8, their own nonlinearity and change in the supply voltage do not affect the spectral purity of the output oscillations, which allows the output sequence to be formed in a wide range of output frequencies. 1 il.

Description

one

(21), 4611086 / 24-09

(22) 11/30/88

(46) 08/30/90. Bksh. No. 32 (72) I.N. Gurevich and Yu.A. Nikitin. (53) -621.373.42 (088.8) (56). US Patent No. 3976945, cl. 2828-14,

USSR author's certificate D 1061235, cl. H 03 B 19/00, 1982.

(54) FREQUENCY SYNTHESIZER

(57) The invention relates to radio engineering. The purpose of the invention is to expand the range of output frequencies. The frequency synthesizer contains a reference oscillator 1, a pulse subtraction unit 2, a counter 3 with a variable conversion factor, the first and second generators

sawtooth voltage (GPN) 4 and T, comparator 5, accumulating adder 6 and adder 7 codes. The steepness of the sawtooth voltage of the first and second FPGs 4 and 8 depends not only on the current delay code x from the output of accumulating adder 6, but also on the number of the synthesized frequency Q defined by the second input of the adder 7. With the same voltage variation law the outputs of the first and second FPGs 4 and 8, their own nonlinearity and variation of the supply voltage do not affect the spectral purity of the output oscillations, which allows the output sequence to be formed in a wide range of output frequencies. 1 il.

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 The invention relates to radio engineering and can be used in radio transmitting, radio receiving devices, as well as in measuring equipment devices.

The purpose of the invention is to expand the range of output frequencies.

The drawing shows a structural electrical circuit of a frequency synthesizer.

The frequency synthesizer contains a reference oscillator 1, an impulse subtraction unit 2, a counter 3 with a variable conversion factor, the first generator J5 of the output of counter 3 was proportional to 4 sawtooth voltage (P1H), ommparator 5, accumulating adder 6, code adder 7, and second GPN 8. i The frequency synthesizer works in the following ipiM manner.20

; The reference 1 generator 1 creates a uniform pulse sequence with a constant frequency f. In the initial state, block 2 of the subtraction passes all pulses to the input 25 of counter 3, which allocates every i-th input load at its fiepBOM output, and every second pulse precedes the i-th output. Impulses; sy from the output of the comparator 5 arrive Q: at the input of the accumulating adder b, -: increasing with each; tick number, written in memory of accumulating adder 6 by the value: k (1, where Q is the capacity of accumulating adder 6.

When the accumulating accumulator 6 overflows, its output overflows; no signal is generated by which the subtraction unit 2 does not pass a single pulse to the input of counter 3. Sum Q Q Q the recalculation coefficient becomes equal to + 1.

Thus, at the first and second outputs of the counter 3, the code at the output of accumulating adder 6 remains quasi-free and does not depend on the number of the synthesized frequency Q. With the same voltage change law, at the outputs of the HPL 4 and -8, their own nonlinearity and change in supply voltage does not affect In the case of using the simplest nonlinear FPG 4 and 8 in the form of a KC circuit (not shown), the resistances of the elements with controlled resistance R are directly proportional to the code x j at the output accumulating first adder 6, and the capacitance C of capacitors constituting the GPN 4 and 8, are chosen identical. Each pulse from the second output of the counter 3 discharges the second GPN 8. At the end of the pulse, the voltage at the output of the second GPN 8 changes exponentially

 and,"; Ed-e-)

where C, TO ();

Q is the number of the synthesized frequency at which the circuit is tuned;

E is the power supply voltage. After time T, a pulse appears on the first output of the periodic pulse pulse counter 3, which

at a given frequency, shifted from one another by the period of the reference oscillation T -.

 o Every pulse on the second exit

counter 3 causes a sawtooth voltage change at the output of the second GPN 8. After time T, the pulse at the first output of counter 3 causes a sawtooth voltage change at the output of the first PN 4. The rise rate of both voltages at the PN 4 and 8 outputs in each. This is different and is determined by the code at the output of the accumulating

first discharges the first gas pump 4. At the end of this pulse, the charge of the capacitor C of the first gas pump 4 with a constant time

 TO. QH -LJo

50 And F d - e) UrnH Ч- ®

The impulse at the output of the comparator 5 is generated at the time of equality of the voltages and 4 of this condition

t T

,

- -. - with g

and the value of the time shift of the output sequence of the synthesizer is

adder 6. However, the rate of increase of voltage at the output of the first GPN

4 higher than the rate of increase of voltage at the output of the second GPN 8. At the time when these voltages become equal, at the output of the comparator

5, a synthesizer output pulse is generated. The difference in the slew rate at the output of the FPG 4 and 8 is chosen equal to Q units, i.e. so that the magnitude of the time shift of the synthesizer output pulses relative to the pulses on the main

first discharges the first gas pump 4. At the end of this pulse, the charge of the capacitor C of the first gas pump 4 with a constant time

 TO. QH -LJo

And F d - e) UrnH × -

The impulse at the output of the comparator 5 is generated at the time of equality of the voltages and 4 of this condition

t T

,

- -. - with g

and the magnitude of the time shift of the output sequence of the synthesizer relative to the sequence at the first output of the counter 3

 3

 tt t,

l

-g

/ - .Q and h

° about Q

The maximum value of the delay when the mox TO Pnna be equal to T, therefore n lla1; with QH QMOIKC-I and

 T. (

X |

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+ about.

Thus, the magnitude of the time shift is directly proportional to the calculated code of the temporal deviation of the pulse at the first output of counter 3 from uniform pulses (hypothesis of a frequency synthesizer containing a series-connected reference oscillator, a pulse subtraction unit, a counter with a variable coefficient

, d recalculation, first sawtooth generator, comparator and accumulating adder, the overflow output and the code output of which are connected respectively to the control

J5 inputs of a pulse subtraction unit and a first sawtooth voltage generator; a second sawtooth voltage generator, which is switched on by a second counter output with a variable recalculation coefficient and a second comparator input, characterized in that, in order to expand the range of output frequencies, between the code output of the accumulator

c) sequence, and t, does not depend on the nonlinear law of voltage rise at the output of the FPG 4 and 8, on the value of the supply voltage E, and on the number of the synthesized frequency Q. As a result, the output sequence of the frequency synthesizer does not differ

from the uniform and does not contain side ", ..opp by the input of the accumulator nocomp ™ (with an ideal-25 adder and control input of the second n. comparator 5) in a wide range of the sawtooth generator, synthesize, x frequencies. ,,,,, „Codes, second entrance

Thus, the introduction of an adder which is the input of control 7 makes it possible to synthesize a grid of frequency-output frequency synthesizer

1589367

Claims (1)

one with high quality in a wide range of output frequencies. Invention Formula Frequency synthesizer containing a series-connected reference oscillator, a pulse subtraction unit, a variable coefficient counter recalculation, the first sawtooth generator, comparator and accumulating adder, the overflow output and the code output of which are connected respectively to the control the inputs of the pulse subtraction unit and the first sawtooth voltage generator, the second sawtooth voltage generator, which is switched on by a second counter output with a variable conversion factor and a second comparator input, characterized in that, in order to expand the range of output frequencies, between the code output of the accumulator ", .. a.in the accumulator accumulator and the control input of the second sawtooth generator ,,,,,," codes, the second input